Data from Delta and Omicron outbreaks show 1 in 15 unvaccinated cases were hospitalised - significantly more than vaccinated

Unvaccinated people were significantly more likely to be hospitalised with COVID-19 than vaccinated during New Zealand's Delta and Omicron outbreaks. 

Dr Leighton Watson, an Auckland-based a geophysicist and mathematician with the University of Canterbury, looked at data from both outbreaks and found unvaccinated COVID cases ended up in hospital much more than vaccinated cases.

For unvaccinated people, 1 in 15 cases were hospitalised during the Delta and Omicron outbreaks compared to 1 in 128 for the double-vaccinated and 1 in 213 for those with boosters. 

The calculations were based on figures from the Ministry of Health which show during the outbreaks there were 7038 unvaccinated cases. Of those 485 were hospitalised giving the hospitalisation rate of one-in-15. 

For single-shot vaccinated people there were 3086 cases and 136 hospitalisations giving the hospitalisation rate of one-in-23. For double-vaccinated Kiwis, despite a whopping 51,810 cases, only 404 were hospitalised, giving a hospitalisation rate of one-in-128. And the statistics were even better for boosted people with 20,491 cases and 96 hospitalisations, giving a hospitalisation rate of one-in-213.

For those who are not eligible (under 12 years old) there were 13,227 cases and 98 hospitalisations giving a hospitalisation rate of one-in-135. 

Watson said it demonstrates the vaccine is effective at keeping people out of hospital, saving lives, and preventing the healthcare system from being overrun. 

"This data provides a useful demonstration of how the vaccine is remarkably effective at keeping people out of hospital," he said. 

And data from the current hospitalisations backs this theory up. 

Watson pointed to the latest Ministry of Health data which showed of the people currently hospitalised with COVID in the northern region, including Auckland and Northland, 36 people (14.3 percent) are unvaccinated or not eligible, 6 people (2.4 percent) are partially vaccinated, 61 (24.2 percent) are unknown and 110 cases (43.7 percent) are fully vaccinated. 

While on the face of it that number might seem alarming, Watson said the vast majority of Kiwis are fully vaccinated. 

New Zealand has high vaccination rates with 95 of the eligible population 12 and up having one dose and 94 percent fully vaccinated. More than 2 million people have also received their boosters jabs. 

Just over 3 percent of eligible people aged 12 and over in Aotearoa are completely unvaccinated, according to the Ministry of Health. But of eligible people in Northland and Auckland hospitals with COVID, 12 percent had no dose indicating that unvaccinated people are four times overrepresented in current hospitalization data. 

Watson calculated how many unvaccinated versus not eligible people are currently in hospital with COVID in the northern region to determine that. 

Watson says based on those calculations there are 4.2 times as many fully vaccinated people in hospital compared to unvaccinated. But there are 27 times as many vaccinated people in New Zealand as unvaccinated. This means that vaccinated people are underrepresented in hospitalization data, and that the vaccine helps keep people out of hospital if they do get infected with COVID.